The multidisciplinary pediatric oncology program at UCLA will participate in the clinical research programs of the Children's Cancer Study Group (CCSG). This will allow UCLA physicians and patients to take part in clinical oncology studies which could not be undertaken in a single institution. The UCLA program focuses upon several areas of current oncologic interest: 1) recurrent lymphoblastic leukemia, 2) myeloblastic leukemia, 3) neuroblastoma, 4) histiocytosis, and 5) the late neurologic sequelae of leukemia and its treatment. UCLA personnel will continue to provide leadership to CCSG in these areas in which our investigators have experience and expertise, and which are relevant to CCSG because the tumors involved have not benefitted from recent advances in the oncologic armamentarium. We shall participate in the development of innovative programs which address the biology, diagnosis and treatment of these tumors. Our extensive experience with tumor immunology and marrow transplantation will be of particular use in pilot treatment programs for treatment of neuroblastoma and leukemia. In addition, we shall provide reference laboratories for immunologic typing of leukemia and lymphoma, a repository for clinical specimens from neuroblastoma patients, and perform marrow transplants for CCSG patients referred by Group institutions that do not have transplant capability. Thus, UCLA will contribute to the cooperative CCSG effort through general participation, the provision of scientific leadership, the initiation and performance of pilot studies, and as resource center for the Group.